PowerPak

The PowerPak is a flash cartridge made by RetroUSB. It uses an FPGA to emulate a wide variety of mappers, allowing the user to store a large collection of ROMs on a single Compact Flash card and run them on an NES. It is widely used by homebrew NES developers to test their software. It's also compatible with the CopyNES.

In addition to NES ROMs, the PowerPak is able to play FDS disk images, as well as NSF music files.

Famicom expansion audio is supported, and output on the EXP 6 expansion pin on the cartridge connector. A simple modification to the NES allows the expansion audio to be mixed with its output.

Contents

Mapper Compatibility

The PowerPak mappers have undergone several revisions, gradually improving compatibility. After official development ceased in 2010, Loopy and TheFox have each created a supplemental set of PowerPak mappers to improve its capabilities.

The commonly recommended setup is:

Begin with the Official mapper set.

Add Loopy's mapper set on top, replacing files.

Add the PowerMapper set on top if you want savestate support (see its readme).

Add any of the additional single mappers if needed.

PowerMappers

TheFox created a set of revised PowerPak mappers to supplement or augment the existing ones, most notably adding a savestate feature for the mappers it contains, but removing the Game Genie feature.

Software development limitations

Aside from mapper incompatibility, there are minor differences between running NES programs on the PowerPak versus a traditional single-game cartridge.

The PowerPak does not accurately simulate power-on state. Because power-on always boots the PowerPak menu, RAM and various registers will be initialized to a consistent state before any NES ROM is chosen to run. (Reset state, however, is not affected by this problem.)

Open bus behavior may be different in several memory regions that are used by the PowerPak, but would not be connected on a regular cartridge. (forum post)

PowerPak development resources

PowerPak Menu - information about the organization of the PowerPak's operating system.